[llama stack ui] add native eval & inspect distro & playground pages

[yanxi0830]

What does this PR do?

New Pages Added:

• (1) Inspect Distro
• (2) Evaluations:
  • (a) native evaluations (including generation)
  • (b) application evaluations (no generation, scoring only)
• (3) Playground:
  • (a) chat
  • (b) RAG

Test Plan

streamlit run app.py

Playground & Inspect

Screen.Recording.2024-11-27.at.4.59.14.PM.mov

Native Evaluations

Screen.Recording.2024-12-02.at.3.59.43.PM.mov

Application Evaluations

Screen.Recording.2024-11-25.at.6.23.53.PM.mov

LLM As Judge for Application Eval

Screen.Recording.2024-12-02.at.1.09.01.PM.mov

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Ran pre-commit to handle lint / formatting issues.
• Read the contributor guideline,
  Pull Request section?
• Updated relevant documentation.
• Wrote necessary unit or integration tests.